This week Al Gore said the obvious. "The media is kind of weird these days on politics," he told The New York Observer, "and there are some major institutional voices that are, truthfully speaking, part and parcel of the Republican Party."

The reaction from most journalists in the "liberal media" was embarrassed silence. I don't quite understand why, but there are some things that you're not supposed to say, precisely because they're so clearly true.

The political agenda of Fox News, to take the most important example, is hardly obscure. Roger Ailes, the network's chairman, has been advising the Bush administration. Fox's Brit Hume even claimed credit for the midterm election. "It was because of our coverage that it happened," he told Don Imus. "People watch us and take their electoral cues from us. No one should doubt the influence of Fox News in these matters." (This remark may have been tongue in cheek, but imagine the reaction if the Democrats had won and Dan Rather, even jokingly, had later claimed credit.)

But my purpose in today's column is not to bash Fox. I want to address a broader question: Will the economic interests of the media undermine objective news coverage?

For most of the last 50 years, public policy took it for granted that media bias was a potential problem. There were, after all, only three national networks, a limited number of radio licenses and only one or two newspapers in many cities. How could those who controlled major news outlets be deterred from misusing their position?

The answer was a combination of regulation and informal guidelines. The "fairness doctrine" forced broadcast media to give comparable representation to opposing points of view. Restrictions on ownership maintained a diversity of voices. And there was a general expectation that major news outlets would stay above the fray, distinguishing clearly between opinion and news reporting. The system didn't always work, but it did set some limits.

Over the past 15 years, however, much of that system has been dismantled. The fairness doctrine was abolished in 1987. Restrictions on ownership have been steadily loosened, and it seems likely that next year the Federal Communications Commission will abolish many of the restrictions that remain — quite possibly even allowing major networks to buy each other. And the informal rule against blatantly partisan reporting has also gone away — at least as long as you are partisan in the right direction.

The F.C.C. says that the old rules are no longer necessary because the marketplace has changed. According to the official line, new media — first cable television, then the Internet — have given the public access to a diversity of news sources, eliminating the need for public guidelines.

But is this really true? Cable television has greatly expanded the range of available entertainment, but has had far less broadening effect on news coverage. There are now five major sources of TV news, rather than three, but this increase is arguably more than offset by other trends. For one thing, the influence of print news has continued its long decline; for another, all five sources of TV news are now divisions of large conglomerates — you get your news from AOLTimeWarnerGeneralElectricDisneyWestinghouseNewsCorp.

And the Internet is a fine thing for policy wonks and news junkies — anyone can now read Canadian and British newspapers, or download policy analyses from think tanks. But most people have neither the time nor the inclination. Realistically, the Net does little to reduce the influence of the big five sources.

In short, we have a situation rife with conflicts of interest. The handful of organizations that supply most people with their news have major commercial interests that inevitably tempt them to slant their coverage, and more generally to be deferential to the ruling party. There have already been some peculiar examples of news not reported. For example, last month's 100,000-strong Washington antiwar demonstration — an important event, whatever your views on the issue — was almost ignored by some key media outlets.

For the time being, blatant media bias is still limited by old rules and old norms of behavior. But soon the rules will be abolished, and the norms are eroding before our eyes.

Do the conflicts of interest of our highly concentrated media constitute a threat to democracy? I've reported; you decide.